The portable biosensor systems have been used for measuring the concentration of an analyte contained in a blood sample (e.g., the concentration of glucose contained in blood, i.e., a blood glucose level). The portable biosensor systems are normally equipped with a measuring instrument including a computation unit and a sensor chip detachably attached to the measuring instrument. The analyte concentration is calculated based on the amount of an oxidant or reductant to be generated in the course of an enzyme cycling reaction mediated by an oxidoreductase for which the analyte serves as a substrate. The speed of the enzyme cycling reaction depends on the temperature of an on-going reaction (reaction temperature). Therefore, it is desirable to correct the analyte concentration based on the reaction temperature.
For example, the reaction temperature is measured by a temperature sensor disposed in the measuring instrument (Patent Literature 1). However, the inner temperature of the measuring instrument is measured in a biosensor system described in Patent Literature 1. In other words, the reaction temperature to be measured does not accurately reflect the temperature of the blood sample. Therefore, errors may be produced in measuring the analyte concentration.
Patent Literatures 2 to 4 describe biosensor systems intended to enhance accuracy of measuring the reaction temperature. The biosensor systems described in Patent Literatures 2 and 3 include a thermal conductive member in the vicinity of a blood sample holder of a sensor chip. A temperature sensor, disposed in a measuring instrument, is configured to detect the blood sample temperature to be transferred through the thermal conductive member. In the biosensor systems described in Patent Literatures 2 and 3, a resin plate is disposed between the thermal conductive member and the blood sample holder. Therefore, the thermal conductive member is prevented from making contact with the blood sample. In the biosensor system described in Patent Literature 4, a temperature sensor and a thermal conductive member are disposed on a sensor chip attachment section of a measuring instrument. The blood sample temperature is transferred to the temperature sensor through the thermal conductive member.